Scratch built 10 cm wooden boat model, the ropes are hand made, the sea is carved out of walnut timber and painted

The sail was made by using very thin wet tissue laid over a light glob and brushed with PVA glue, 2 or 3 layers of tissue and glue. Then the best section was cut out with scissors. It comes off the light glob fairly easy.

          

All the characters on this page with the exception of the last one (there were 5 in total, 3 shown here) I produced for the promotion of a series of children's books, published by Murdoch Books Australia.

The original characters were created by Emily MacMahon  which I then added to and modified so they could be created as actual models for the promotion.

Greedy Gutz on the left is about 27 cm high and is made mostly of plastic. Here he is coated in car under paint waiting to be painted with his finished colours. That little yellow thing on his nose is a copper ring. The chain belt is a real metal one stuck there with super glue. The whole character is made up of  about 15 parts including pins (brass ones).As you can see from the pic below, the parts are made separate, cleaned, partly repaired if necessary and assembled, 3 models were required of each.

                     
Here you can see Russel well on the way to completion. Note the glasses and the small blue radio calculator type thingy  in the foreground that still need to be put on the models.

Now for some interesting info on How
The Casting material
The plastic I use is a 50/50 mix of clear casting resin and Plastic Bond. I needed a mix that was thick yet able to flow in the mould. Plastic bond is a thick pasty material that is used to repair items, probably a little like car body filler (car body filler might also work but I have not tried it). The Plastic bond can be thinned down with a thinner but for my purposes that did not work as the setting time became very long. I found the casting resin as thin as water and could not be tumbled inside of a plaster mould to produce a hollow cast.

I needed a middle stage. One were the mix was already thick but flow able and it had to set within a reasonable time as I can not tumble a heavy plaster mould in my hands all day. It also was not to have a sticky surface as happens with resin unless you exclude air which in this case was not possible. The liquid casting resin when mixed with the stiff Plastic Bond answered the problem.

Solution
The Plastic Bond plus casting resin mix answered all the requirements well.
Thick but flow able
20 minute setting time. The point were it stopped flowing.
Non sticky after release.
No cracking of the plastic cast. I have made some solid casts of large surface area 9 x 6 x 3/4 of an inch , no cracking or warping.
The stuff sets solid before it gets hot, so you can put it down without burning yourself.
It is solid enough to remove from the mould before it is so hot that you physically can not touch it with your hands, With some casting techniques this is a very important point as certain moulds can not stand heat.


Inspired by the Movie "Lord of the rings"


The Mould: Plaster or Gelatine
Lets start with plaster.
Lets assume you have a plaster piece
mould of the item you wish to reproduce in plastic resin and you want
to tumble it to coat the inside with the plastic to make a hollow
plastic cast. First word of warning, this is not a fun exercise, it is
heavy hard work that needs constant concentration and manipulation of
the mould to evenly coat the interior, Tumble gives a overly simplistic
name to the technique, You have to tumble the heavy wet (with water)
and part filled with plastic resin inside of the plaster mould for as
long as it takes to set (usually 20 minutes but if it takes an hour
that's too bad, keep moving it) without getting intoxicated by the very
nasty fumes.

This may be quite different to other descriptions by others but this one
actually works in practice, do it another way and chances are it will not
come out of the plaster mould. Soak the mould in water, totally at
least for 10 minutes, pull it out, let it sit till it is not shiny but
dull. Coat the inside using a brush and liquid soap. Let it soak in, no
puddles, now use a good car wax polish  and rub it in well. Put
mould back together, tie with string and seal seams with clay. Pour in
the right amount (that's up to you) and start tumbling till it sets. I
have found that if I remove the cast before it gets to hot it always
comes out, on the other hand if I wait till it has all cooled down
there have been occasions were it got so stuck that the plaster had to
be destroyed to remove it. If you skip the water soaking it is
guaranteed to get stuck. The water has no ill affect on the setting
resin. Do not do this in the winter as the air temperature should at
lest be warm or you resin may not set properly.
the rounded black plastic base was made by pouring black coloured casting resin
and plastic bond mix into the bottom of a suitably shaped and sizes plastic food container,
(buy the way I mixed Perlite with it to keep the weight down) let it set, pop it out,
sand the top which will become the bottom flat and stick a cork sheet to the bottom.
The top gets screws in it to give the plaster landscape a grip.

Plasticine head.
This is the item that is immersed in the gelatine.
Note that the item you make or an item you found don't need to be made of plasticine, they can be made of anything. You will however have to experiment to find out what to coat your original with without destroying it. It will probably need a release agent of come kind (Plasticine does not need any release agent), Keep in mind that if your original is porous, say balsa wood it will probably tear away the surface of the gelatine as it will soak it up, become glued to it, so you will have to , oil, or shellac it which will change your original for ever.

Gelatine mould
The head above was cast in plaster.
The mould however was Gelatine. Yes
ordinary food Gelatine and Greedy Guts at the top of this page was
plastic Bond and casting resin mix poured into a Gelatine mould. It
gives beautiful results, is cheep and is reusable (as in melt it down
to make a new mould, you can use it over and over,) . Yes you could use
Silicon rubber and it has it's uses but the advantage with Gelatine is
it sets faster and can be used in hours as opposed to silicon that
usually requires 24 hour to cure. Gelatine has a natural release, it
never gets stuck. Silicon rubber can be used over and over for the same
mould but requires special coatings to protect it from resin as it does
break it down. Silicon is very very expensive compared to
Gelatine. 

Close up of the plaster cast which came out of a gelatine mold. Note I did sharpen up some of the detail on the plaster cast, it is an art process, not a mass production process. I then painted it with airbrush and acrylics. By the way The same goes for Greedy guts at the top of the page. There is a lot of putting together to be done, cleaning edges etc. If your expecting to cast it, pop it out and your done then your living in a fantasy world.
I find I get great results with it.

The Gelatine mould technique is hundreds of years old. One of it's uses was to make wax cast's (hollow) of sculptures that were then reassembled into one total hollow wax statue the inside of which was filled with a weak investment plaster and the whole wax statue embedded in plaster with air vents and pins. It is put in the oven and the wax melts out.  The space is then replaced with molten bronze. The process is known as the lost wax process which seems to be misunderstood by many buyers and promoted by some unsound dealers and galleries promoting the idea or process as a lost art or a lost technique. Nothing could be more from the truth. It is not lost, it is used today, what is lost is that the wax melts away. Sorry if this removes some of the mystery but I don't have time for con men.

It's a complicated but logical  process and I am sure I have omitted things, if there is an interest I will put an in depth description. But to get back to the process, the Gelatine is heated in a double boiler Don't boil it. The stuff I use comes in grain form so I add enough water to only wet it, I don't dissolve it in water, just enough to wet it. Now heat it till it melts. I use a candy thermometer to measure the heat. Be careful you don't spill it on yourself or you will get severe burns as it sticks like tar. If your model is made of Plasticine as mine was, let it cool to 37 degrees Celsius and pour it around the model, not directly on the model or you might melt it away, 37 degrees C works for me and it does not melt. Let it set, put it in the frig to speed it up.

The head lying on it's side just above. This Plasticine had a thin thread stuck around it's head, up the left side ,over the top and down the right. The whole thing was then suspended ,fully immersed in molten gelatine and allowed to set. The whole thing was then taken out of the container and the thread ends gently pulled so that the Gelatine was in two half's. They were then gently pulled away from the original helping it around overhangs and undercuts.

The Gelatine is very elastic, and if you think of the jelly or if you are American jello that you eat it would seem impossible. But it is the same stuff. It  feels more like rubber  as it contains only little water, it also does not contain any sugar or flavoring , it is food Gelatine.

Put it back together, it helps if you make a wave cut so you can key it.

The greedy Gutz body was cast solid, just pour it full and let it set. If you are very good you can make multiple casts from the one mould. I managed two, on the second I was not fast enough and the heat melted the gelatine, I pulled out the part, washed it in water and it was ready to use. I had to remake the Gelatine mould for the third one by using the now molten Gelatine over the original again to make a new mould. That's one of the disadvantages of Gelatine with plastic. It often melts as the cast sets, but the cast comes out perfect in every detail so if you only need one for a prototype it's a great material.

To store it, keep it in the frig, pour olive oil on it to keep the air away. It does develop mould, even under the oil, just pour off the oil and scrap off the mould and heat it to use again, add a little water from it to time as it looses during heating.

If you cast in plaster you first need to brush the inside carefully with alum so that the surface is a little resistant to water, a little rub down with olive oil does not hurt as it stops the gelatine swelling with water from the plaster. It seems like a strange combination but it works, the cast comes out great as can be seen and you are able to make casts quickly in plaster that you can develop more if you wish. Try doing that with a plaster waste mould, on small objects waste moulds tend to cause breaks all over the place when trying to chip out the cast.

have no objection to sharing my knowledge but I do object to those few who would seek a financial profit on my hard work without my permission and without remuneration for my service.

So it has become necessary to include copyright and licence agreements to afford myself some protection as to my property rights. I dislike these additions as much as you do.

Note that I am not claiming copyright for any methods shown as I believe it is the right of any person to use them for private use or commercial use.
What my copyright refers to is that the article as I have written it is mine, so are the graphics. You are free to use the techniques however for whatever you want. Just don't be lazy and reuse this article for commercial use. Use the techniques but use your own words, your own graphics and hopefully add your own discoveries. That means don't write about this stuff unless you have tired it and found it to work as too many books exist out there written by unbelievably lazy people that have no idea about what they are writing about, so don't become yet another one of them. There is more then enough confusion out there already.

Copyright Mario Donk